Correct Option :- (d) zero
Explanation :-
Here δ = 30º, A = 60º
so if the prism had been in a minimum deviation
μ = sin {(A+δm)/2}/ sin (A/2)
μ = sin {(60+30)/2}/ sin (60/2)
μ = sin 45º/ sin 30º
μ = (1/√2)*2 = √2
Refractive index of prism is also given as √2,
the prism is in the position of minimum deviation.
This in turn implies that r1 = r2=r = A/2 = 60/2 = 30º
So the angle subtended by the ray inside the prism with surface AB is equal to
90-r1 = 90-30 = 60º
As base also subtends an angle of 60º with the face AB.
Hence the ray inside the prism is parallel to the base.
i.e. the angle subtended by the ray inside the prism with the base is zero.